U.S. patent application number 10/915568 was filed with the patent office on 2005-09-29 for optical wavelength division multiplexing transmission system.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Hashizume, Masato, Iwaki, Hiroyuki, Okano, Hisanori, Shibata, Megumi, Yasui, Takanori.
Application Number | 20050213967 10/915568 |
Document ID | / |
Family ID | 34989947 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050213967 |
Kind Code |
A1 |
Okano, Hisanori ; et
al. |
September 29, 2005 |
Optical wavelength division multiplexing transmission system
Abstract
If wavelengths .lambda.a and .lambda.b are dropped in NE
(Network Equipment) 2 and a wavelength .lambda.c is made Through,
and all of wavelengths are made Through in NE3 in a certain time
period, a route from NE1 to NE2, a route from NE2 to NE4, and a
route from NE1 to NE4 are established. If a user who uses the
wavelength .lambda.a from NE1 to NE2, and a user who uses the
wavelength .lambda.b from NE2 to NE4 do not use the routes in
another time period, and if another user desires to use a route
from NE1 to NE3 and a route from NE3 to NE4, the routes are
reestablished in a way such that the wavelength .lambda.a is
converted into the wavelength .lambda.b and made Through in NE2,
and the wavelength .lambda.b is dropped and added in NE3.
Inventors: |
Okano, Hisanori; (Yokohama,
JP) ; Iwaki, Hiroyuki; (Yokohama, JP) ; Yasui,
Takanori; (Yokohama, JP) ; Hashizume, Masato;
(Yokohama, JP) ; Shibata, Megumi; (Kameoka,
JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
FUJITSU LIMITED
Kawasaki
JP
|
Family ID: |
34989947 |
Appl. No.: |
10/915568 |
Filed: |
August 11, 2004 |
Current U.S.
Class: |
398/30 |
Current CPC
Class: |
H04J 14/0212 20130101;
H04J 14/0241 20130101; H04J 14/0217 20130101; H04J 14/028 20130101;
H04J 14/0227 20130101 |
Class at
Publication: |
398/030 |
International
Class: |
H04B 010/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2004 |
JP |
2004-095908 |
Claims
What is claimed is:
1. An optical wavelength division multiplexing transmission system,
where a plurality of transmission devices are connected, wavelength
division multiplexing and transmitting a plurality of wavelengths,
each of the plurality of transmission devices comprising: a
switching unit switching a path of an optical signal having each
wavelength; a wavelength converting unit converting a wavelength of
an optical signal; and a controlling unit converting a wavelength
of an optical signal, switching a path, and transferring the
optical signal based on information from a supervisory control
signal in order to form a desired path by connecting unused paths
in a predetermined time period.
2. The optical wavelength division multiplexing transmission system
according to claim 1, wherein said control unit comprises a memory
unit storing setting information of wavelengths.
3. The optical wavelength division multiplexing transmission system
according to claim 2, wherein the setting information of
wavelengths is transmitted from a predetermined transmission device
to all of the other transmission devices.
4. The optical wavelength division multiplexing transmission system
according to claim 2, wherein when a predetermined time period
based on a time table also stored by said memory unit is reached,
each of the transmission devices automatically executes a process
for converting a wavelength, and for switching a path based on the
setting information of wavelengths.
5. The optical wavelength division multiplexing transmission system
according to claim 2, wherein each of the transmission devices
automatically executes a process for converting a wavelength, and
for switching a path according to a trigger signal transmitted from
a predetermined transmission device based on the setting
information of wavelengths.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical wavelength
division multiplexing (WDM) transmission system.
[0003] 2. Description of the Related Art
[0004] With the popularization of communications technology using a
computer, the volume of traffic to be accommodated by a
communications system has been rapidly increasing. As a system that
can accommodate such traffic, an optical wavelength division
multiplexing transmission system is known.
[0005] FIG. 1 exemplifies the general configuration of a wavelength
division multiplexing transmission system.
[0006] An NE (Network Equipment) ion a transmitting side is
configured by a MUX unit 10 multiplexing wavelengths .lambda.1 to
.lambda.n, a TA (Transmitting Amplifier) unit 11 optically
amplifying a WDM optical signal output from the MUX unit 10, and an
OSC (Optical Supervisory Channel) unit 12 conveying optical signal
information, various items of OH (OverHead) information and device
information. An OSC optical signal is multiplexed with an optical
signal output from the TA 11, and output from the NE 1. The NE2 and
an NE3 respectively comprise OSC units 15 and 16 receiving and
transmitting an OSC optical signal, an RA (Receiving Amplifier)
unit (not shown) optically amplifying WDM optical signals from all
of NEs, and an XC (CrossConnect) unit 13 or 14 enabling some of the
signals to be split and output, or to pass through, and also
enabling input optical signals to be coupled. An NE4 is configured
by an OSC unit 17 receiving an OSC optical signal, an RA unit 18
optically amplifying the signal further, and a DMUX unit 19
demultiplexing the signal into wavelengths .lambda.1 to .lambda.n.
This system includes systems transmitting an optical WDM signal to
an opposite side each other. Since the configuration of the system
transmitting an optical signal to the side opposite to the
direction where the optical signal is transmitted is also similar
to the above described configuration, its explanation is
omitted.
[0007] As conventional optical WDM systems, Patent Documents 1 and
2 exist. Patent Document 1 discloses a WDM system forcibly
releasing a wavelength path having a low priority, and establishing
a wavelength path when the volume of traffic of a wavelength path
of a user having a high priority becomes heavy. Patent Document 2
discloses an optical WDM system that can add a new line, and can
effectively set up an unused line without affecting a line in
use.
[0008] [Patent Document 1] Japanese Patent Publication No.
2002-135308
[0009] [Patent Document 2] Japanese Patent Publication No.
2003-174432
[0010] In conventional optical WDM systems, if there is a line that
a user does not use in a particular time period or on a particular
date and time, and if the line is considered to be made available
to another user in the time period during which the line is unused,
it cannot be used even if a user considers the use of a route other
than an established route. This is because route setting for each
wavelength is fixed.
[0011] FIG. 2 explains the conventional problem.
[0012] For example, if a user desires to use a route from the NE1
to the NE3, and a route from the NE3 to the NE4 in a time period
during which another user who uses .lambda.a (A shown in FIG. 2)
from the NE1 to the NE2, and .lambda.b (B shown in FIG. 2) from the
NE2 to the NE4 does not use these wavelengths, these wavelengths
cannot be used despite their existence.
SUMMARY OF THE INVENTION
[0013] An object of the present invention is to provide a WDM
transmission system that enables another user to use a line in a
certain time period by contract, and also enables an arbitrary
route setting by performing wavelength conversion depending on a
time period in each NE.
[0014] An optical WDM transmission system according to the present
invention is an optical wavelength division multiplexing
transmission system, where a plurality of transmission devices are
connected, wavelength-division multiplexing and transmitting a
plurality of wavelengths. Each of the transmission devices is
characterized in comprising a switching unit switching a path of an
optical signal having each wavelength, a wavelength converting unit
converting a wavelength of an optical signal, and a controlling
unit converting a wavelength of an optical signal, switching a
path, and transferring the optical signal based on information from
a supervisory control signal in order to form a desired path by
connecting unused paths in a predetermined time period.
[0015] According to the present invention, if a wavelength that is
unused in a certain time period occurs by contract, this wavelength
is allocated to another user, and wavelength-converted, whereby a
route can be formed and made available to the other user.
Accordingly, network resources can be effectively used, and a user
can make a contract for the use fee of network resources depending
on a time period, whereby the user does not need to pay an extra
contract fee.
DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 exemplifies a general configuration of a WDM
transmission system;
[0017] FIG. 2 explains a conventional problem;
[0018] FIG. 3 explains the principle of a configuration
implementing a preferred embodiment according to the present
invention;
[0019] FIG. 4 shows the details of an XC unit according to the
preferred embodiment of the present invention;
[0020] FIG. 5 explains the preferred embodiment according to the
present invention;
[0021] FIG. 6 exemplifies an operation performed by the XC unit
based on information from a management unit, according to the
preferred embodiment of the present invention;
[0022] FIG. 7 shows a system configuration (No. 1) for implementing
a first preferred embodiment according to the present
invention;
[0023] FIG. 8 shows a system configuration (No. 2) for implementing
the first preferred embodiment according to the present
invention;
[0024] FIG. 9 is a flowchart showing operations performed in the
case of FIGS. 7 and 8;
[0025] FIG. 10 shows and explains a system configuration for
implementing a second preferred embodiment according to the present
invention;
[0026] FIG. 11 is a flowchart explaining a process executed by a
management NE;
[0027] FIG. 12 is a flowchart explaining a process executed by an
NE to be managed;
[0028] FIG. 13 shows and explains a system configuration for
implementing a third preferred embodiment according to the present
invention;
[0029] FIG. 14 is a flowchart explaining a process executed by each
NE, according to the third preferred embodiment;
[0030] FIG. 15 explains a system configuration and operations for
implementing a fourth preferred embodiment according to the present
invention;
[0031] FIG. 16 is a flowchart explaining a process executed by each
NE, according to the fourth preferred embodiment of the present
invention;
[0032] FIG. 17 is a flowchart showing the details of a process
executed by an SW unit; and
[0033] FIG. 18 is a flowchart showing the operations of a
wavelength converting unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0034] FIG. 3 explains the principle of a configuration
implementing a preferred embodiment according to the present
invention.
[0035] A coupler CPL 25 is a coupler coupling WDM and OSC optical
signals having different wavelengths. An E/O Mod 26 is a module
converting an electric signal into an optical signal, whereas an
O/E Mod 27 is a module converting an optical signal into an
electric signal. To an NE1 on a transmitting side, optical signals
having wavelengths .lambda.1 to .lambda.n are input, and
multiplexed by a MUX unit 28, so that WDM light is generated.
Furthermore, the WDM light is coupled with an OSC optical signal by
the coupler CPL 25, and transmitted to a transmission path. For the
OSC optical signal, a corresponding electric signal is first
generated by an OSC processing unit of a management unit 32. The
OSC processing unit generates an OSC signal with the electric
signal based on various items of information stored in a memory,
transmits the OSC signal to a control circuit of an OSC unit 29,
which controls the E/O Mod 26 converting an electric signal into an
optical signal, so that the OSC optical signal is generated. The
OSC optical signal is coupled with a main signal by the coupler
CPL. Additionally, a splitter CPL 31 on a receiving side splits an
OSC optical signal from a transmitted optical signal, and transmits
the split signal to the O/E Mod 27. Here, the optical signal is
converted into an electric signal, and input to the OSC processing
unit of the management unit 32 via a control circuit of an OSC unit
30. The OSC signal is processed here. Namely, information included
in the OSC signal is analyzed based on information stored in the
memory, and newly transmitted as an OSC optical signal from the
transmitting side, or used to control the NE1.
[0036] An NE2 is a transmission device on the way of a transmission
path. When a transmitted WDM optical signal enters the NE2, an OSC
optical signal is split by a splitter CPL 40. After a main signal
is amplified by an optical amplifier 56, it is demultiplexed into
optical signals having respective wavelengths by a DMUX unit 49,
and input to an XC unit 50. In the meantime, the OSC optical signal
split by the splitter CPL 40 is converted into an electric signal
by an OSC unit 41, and transmitted to a management unit 42. The
management unit 42 analyzes information included in the OSC optical
signal, transmits the information to the XC unit 50, and instructs
the switching of an optical path, etc. The XC unit 50 has a
function to perform any of Add, Drop, Through, and wavelength
conversion operations based on the information from the OSC unit
41. A SW unit 51 is intended to change an optical path. The SW unit
51 switches the optical path of an optical signal input from the
DMUX unit 49, outputs the signal to the Drop side or the side of
the MUX unit 53 or 54, or input to a wavelength converting unit 52.
Additionally, the SW unit 51 outputs the optical signal input from
the Add side or from the DMUX unit 55 to the MUX unit 53 or 54, and
outputs the optical signal input from the wavelength converting
unit 52 to the MUX unit 53 or 54. After the optical signal output
from the MUX unit 53 is amplified by an optical amplifier 57, it is
coupled with the OSC optical signal by a coupler CPL 45, and
transmitted to a transmission path. Also in an optical transmission
system on the opposite side, an OSC optical signal is split by a
splitter CPL 48, and converted into an electric signal by an OSC
unit 47 in a similar manner. The electric signal is analyzed by the
management unit 42, and used to control the operations of the XC
unit 50. A main signal output from the splitter CPL 48 is amplified
by an optical amplifier 58, demultiplexed into optical signals
having respective wavelengths by a DMUX unit 55, and input to the
XC unit. The respective optical signals output to the side of the
MUX unit 54 are multiplexed, and amplified by an optical amplifier
59. The amplified signal is coupled with the OSC optical signal by
a coupler CPL 44, and transmitted to a transmission path.
[0037] FIG. 4 shows the details of the XC unit according to the
preferred embodiment of the present invention.
[0038] A WDM optical signal coming from the input side is amplified
by the optical amplifier 56, and demultiplexed into optical signals
having respective wavelengths by the DMUX unit 49. The
demultiplexed optical signals are input to a branch unit 68 of the
SW unit 51. The branch unit 68 transmits the optical signals to the
Drop side or a coupling unit 69, or to the wavelength converting
unit 52. In the wavelength converting unit 52, the optical signals
having respective wavelengths are converted into electric signals
by an O/E converting unit 66, output ports are switched by a
switching unit 65, and the signals are converted into optical
signals having wavelengths different from the original wavelengths
by an E/O converting unit 67, and input to the coupling unit 69. In
the coupling unit 69, the optical signal from the branch unit 68,
the optical signal from the wavelength converting unit 52, and the
optical signal from the Add side are output to the MUX unit 53. The
MUX unit 53 multiplexes the optical signal having the respective
wavelengths and transmits the multiplexed signal via the optical
amplifier 57.
[0039] According to the preferred embodiment of the present
invention, setting information such as Add/Drop/Through/wavelength
conversion, etc. of an optical signal in each NE is managed for
each time, and transmitted to an NE by using an OSC optical signal,
and wavelength setting is made by controlling the XC unit of each
NE, whereby an idle route varying depending on a time period is
arbitrarily set.
[0040] FIG. 5 explains the preferred embodiment according to the
present invention.
[0041] In the preferred embodiment according to the present
invention, as shown in FIG. 5, an optical signal having a
wavelength .lambda.a from the NE1 to the NE 2 is
wavelength-converted into a wavelength .lambda.b (A shown in FIG.
5) in a certain time period, and transmitted by using an optical
signal having the wavelength .lambda.b from the NE2 to the NE3 (C
shown FIG. 5). In this way, the wavelength of an optical signal
having an available wavelength in a certain time period is
switched, and a route on which the signal is transmitted is allowed
to be arbitrarily set to another route only in that time period. In
this way, a user who desires to temporarily use various routes can
also be flexibly supported.
[0042] In this preferred embodiment, unlike conventional methods, a
wavelength that is not used during a certain time period is
released to another user, thereby reducing communications cost, and
route settings with a higher degree of arbitrariness can be made by
switching a wavelength. As a result, a user who desires various
routes can also be flexibly supported, and a service with a higher
degree of arbitrariness can be provided.
[0043] FIG. 6 exemplifies the operations performed by the XC unit
based on the information from the management unit, according to the
preferred embodiment of the present invention.
[0044] The information from the management unit instructs that
optical signals having respective wavelengths are to be branched to
any of the Through, Drop, and converting units in the branch unit.
Additionally, in the coupling unit, the information from the
management unit instructs that an optical signal having a
wavelength from one of the Through, Add, and converting units is to
be coupled. Furthermore, the information from the management unit
is used as information for converting a wavelength into an electric
signal as O/E conversion information, information for converting a
wavelength into an electric signal, namely, switching information
for outputting a signal from an input port to an output port as
wavelength conversion information, or information for a line to
which conversion into an optical signal is made as E/O conversion
information in the wavelength converting unit.
[0045] That is, the switching of the XC unit is controlled by the
information from the OSC unit. This information is described.
[0046] The switching is implemented by transmitting line setting
information from the management unit to the XC unit in a set time
period T1. The line setting information falls into the branch
information and coupling information for controlling the SW unit,
the O/E conversion information and the E/O conversion information
for controlling the wavelength converting unit, and the conversion
information for converting into a wavelength.
[0047] The branch unit branches .lambda.x input from the DMUX unit
based on received branch information. In the case of Through,
.lambda.x is branched to the coupling unit. In the case of Drop,
.lambda.x is branched to the Drop side. In the case of wavelength
conversion, .lambda.x is branched to the wavelength converting
unit.
[0048] The coupling unit transmits .lambda.x to the MUX unit based
on received coupling information. In the case of Through, .lambda.x
from the branch unit is coupled. In the case of Add, .lambda.x on
the Add side is coupled. In the case of wavelength conversion,
.lambda.x from the wavelength converting unit is coupled.
[0049] The wavelength converting unit converts the input wavelength
.lambda.x into another wavelength .lambda.y according to the
received O/E conversion information, E/O conversion information,
and conversion information. .lambda.x input from the branch unit is
converted into an electric signal Ex according to the O/E
conversion information by the O/E converting unit. The converted
electric signal Ex is switched to the E/O converting unit
converting into the optical signal .lambda.y according to the
conversion information by the switching unit. The electric signal
Ex input to the E/O converting unit converting into .lambda.y is
converted into the optical signal .lambda.y according to the E/O
conversion information, and transmitted to the SW unit.
[0050] A case where the wavelength .lambda.1 on the input side is
made Through to the output side, and .lambda.2 on the input side is
converted into .lambda.3 on the output side and made Through, the
wavelength .lambda.2 on the output side is added, and .lambda.4 on
the input side is dropped and added to the output side is
explained.
[0051] Branch information is transmitted to the branch unit, and
.lambda.1, .lambda.2, and .lambda.4 are respectively branched to
the coupling unit, the side of the converting unit, and the Drop
side according to the information. Coupling information is
transmitted to the coupling unit, and .lambda.1 from the branch
unit, .lambda.2 from the Add side, .lambda.3 from the side of the
converting unit, and .lambda.4 from the Add side are coupled to the
MUX unit according to the information.
[0052] In the wavelength converting unit, O/E conversion
information is transmitted to the O/E converting unit, and
.lambda.2 is converted into an electric signal. Wavelength
conversion information is transmitted to the switching unit, and
the electric signal converted from .lambda.2 is transmitted to the
E/O converting unit converting into .lambda.3. E/O conversion
information is transmitted to the E/O converting unit, which
converts the electric signal into an optical signal having a
wavelength .lambda.3.
[0053] These items of information are transmitted to make a set
switching at a preset time, whereby a switching operation based on
time is performed.
[0054] FIGS. 7 and 8 show system configurations for implementing a
first preferred embodiment according to the present invention.
[0055] An XC unit having a wavelength conversion function exists in
each of NEs. A user .alpha.1 (A shown in FIG. 7) who uses a
wavelength .lambda.a from the NE 1 to the NE 2, and a user .alpha.2
(B shown in FIG. 7) who uses a wavelength .lambda.b from the NE 2
to the NE 4 exist in a time period T1. If a user .beta.1 desires to
use a route from the NE1 to the NE3 in a time period T2 during
which the users .alpha.1 and .alpha.2 do not use the corresponding
wavelengths, the XC unit of the NE2 wavelength-converts .lambda.a
received from the NE1 into .lambda.b, and transmits .lambda.b to
the NE3 (A shown in FIG. 8) in order to secure the route from the
NE1 to the NE3. The NE3 drops .lambda.b received from the NE2 (B
shown in FIG. 8). When the time period T1 during which the users
.alpha.1 and .alpha.2 uses the wavelengths is reached, the settings
are restored to the original ones. Also the settings from the NE4
to the NE1 are similar to the above described ones.
[0056] FIG. 9 is a flowchart showing operations performed in the
case of FIGS. 7 and 8.
[0057] The following process is a process executed by the
management unit.
[0058] In step S10, the management unit determines whether or not
setting information is received. If the setting information is
determined not to be received in step S10, the setting information
is waited to be received. If the setting information is determined
to be received in step S10, the management unit determines whether
or not a time period T2 during which line setting is to be switched
is reached. If the time period T2 is determined not to be reached,
the original line setting T1 is made in step S12, and the process
is terminated. If the time period T2 is determined to be reached in
step S11, line setting T2 is made in step S13, and the process goes
back to step S11. The line setting T2 is maintained until the time
period T2 expires.
[0059] FIG. 10 shows and explains a system configuration for
implementing a second preferred embodiment according to the present
invention.
[0060] An NE1 set as a management NE transmits a wavelength setting
instruction to all of NEs by using an OSC signal, whereby the
wavelengths of the NEs are altogether set. If a user .alpha.1 who
uses a route from the NE1 to an NE2, and a user .alpha.2 who uses a
route from the NE2 to an NE4 exist in a time period T1, and if a
user .beta.1 who uses a route from the NE1 to an NE3, and a user
.beta.2 who uses a route from the NE3 to the NE4 exist in a time
T2, the NE1 set as the management NE transmits a line setting
instruction T1 (A shown in FIG. 10) to the NE2 and the NE3, which
are to be managed, by using an OSC signal. The NE2 sets .lambda.a
and .lambda.b to Add/Drop according to the received setting
instruction to Add/Drop (.lambda.c is always Through). The NE3 sets
.lambda.b to Through according to the received setting instruction
(.lambda.a and .lambda.c are always Through). In this way, the
settings of the time period T1 are completed. When the time period
T2 is reached, the NE1 transmits a line setting instruction T2 (B
shown in FIG. 10) to the NE2 and the NE3 by using an OSC signal.
The NE2 wavelength-converts the received .lambda.a into .lambda.b
according to the setting instruction, and transmits .lambda.b to
the NE3. Namely, .lambda.b is dropped, and the added wavelength
.lambda.a is converted into .lambda.b. The NE3 sets .lambda.b to
Add/Drop according to the setting instruction. Also the settings
from the NE4 to the NE1 are similar to the above described
ones.
[0061] FIG. 11 is a flowchart explaining the process executed by
the management NE.
[0062] The following process is the process executed by the
management unit.
[0063] In step S15, a time period is waited. If the time period T1
is determined to be reached in step S16, the line setting
information T1 is transmitted in step S17. Then, in step S18, it is
determined whether or not a setting completion notification is
received. If the setting completion notification is determined not
to be received in step S18, the process goes back to step S17 where
the line setting information T1 is retransmitted. If the setting
completion notification is determined to be received in step S18,
the process is terminated. If the time period T2 is determined to
be reached in step S19, the line setting information T2 is
transmitted in step S20. Then, in step S21, it is determined
whether or not a setting completion notification is received. If
the setting completion notification is determined not to be
received in step S21, the process goes back to step S20 where the
line setting information T2 is retransmitted. If the setting
completion notification is determined to be received in step S21,
the process is terminated.
[0064] FIG. 12 is a flowchart explaining a process executed by an
NE to be managed.
[0065] The following process is the process executed by the
management unit.
[0066] In step S25, it is determined whether or not setting
information is received. If the setting information is determined
not to be received in step S25, the setting information is waited
to be received. If the setting information is determined to be
received in step S25, line setting is made in step S26. Then, in
step S27, a setting completion notification is transmitted, and the
process is terminated.
[0067] FIG. 13 shows and explains a system configuration for
implementing a third preferred embodiment according to the present
invention.
[0068] A time table of setting information is preset in each of the
NEs. Each of the NEs individually makes wavelength settings
according to this time table, whereby the wavelengths of the NEs
are altogether set. If a user .alpha.1 who uses a route from the
NE1 to the NE2, and a user .alpha.2 who uses a route from the NE2
to the NE4 exist in a time period T1, and if a user .beta.1 who
uses a route from the NE1 to the NE3, and a user .beta.2 who uses a
route from the NE3 to the NE4 exist in the time period T2, each of
the NEs makes wavelength settings according to the time table in
the time period T1. The NE2 sets .lambda.a and .lambda.b to
Add/Drop, and also sets .lambda.c to Through according to a time
table (A shown in FIG. 13). The NE3 sets .lambda.a, .lambda.b, and
.lambda.c to Through according to a time table (B shown in FIG.
13). As a result, the settings of the time period T1 are completed.
When the time period T2 is reached, each of the NEs makes
wavelength settings according to a set time table. The NE2
wavelength-converts .lambda.a into .lambda.b, transmits .lambda.b
to the NE3, drops .lambda.b, and adds .lambda.a according to the
time table (A shown in FIG. 13). The NE3 sets .lambda.b to
Add/Drop, and also sets .lambda.a and .lambda.c to Through
according to the time table (B shown in FIG. 13). Also the settings
from the NE4 to the NE1 are similar to the above described ones.
The settings of a time table in each of the NEs can be changed from
all of the NEs by using an OSC optical signal.
[0069] FIG. 14 is a flowchart explaining the process executed by
each NE according to the third preferred embodiment.
[0070] Step S30 is waiting for an event to occur. If the time
period T1 is determined to be reached in step S31, the line setting
T1 is made in step S32. Then, in step S33, a completion
notification of the line setting T1 is transmitted to the
management NE. In step S34, it is determined whether or not the
completion notification of the line setting T1 is received. If the
completion notification is determined to be received in step S34,
the process is terminated. If the completion notification is
determined not to be received, an alarm is given. If the time
period T2 is determined to be reached as in step S35, the line
setting T2 is made in step S36. In step S37, a completion
notification of the line setting T2 is transmitted. In step S38, it
is determined whether or not the completion notification of the
line setting T2 is received. If the completion notification is
determined to be received, the process is terminated. If the
completion notification is determined not to be received, an alarm
is given. If a time table rewrite instruction is received as in
step S39, the time table is rewritten in step S40, and the process
goes back to step S30.
[0071] FIG. 15 shows and explains a system configuration and
operations for implementing a fourth preferred embodiment according
to the present invention.
[0072] A time table of setting information is preset in each of
NEs. An NE1 set as a management NE transmits a switching trigger to
all of the NEs by using an OSC optical signal, whereby the NEs
altogether set wavelengths according to a time table. If a user
.alpha.1 who uses a route from the NE1 to the NE2, and a user
.lambda.2 who uses a route from the NE2 to the NE4 exist in a time
period T1, and if a user .beta.1 who uses a route from the NE1 to
the NE3, and a user .beta.2 who uses a route from the NE3 to the
NE4 exist in a time period T2, the NE1 set as the management NE
transmits a switching trigger TRG1 (C shown in FIG. 15) to the
respective NEs by using an OSC optical signal in the time period
T1, and the respective NEs make wavelength settings by using the
trigger as a cue according to the set time table. The NE2 sets
.lambda.a and .lambda.b to Add/Drop, and also sets .lambda.c to
Through according to a time table (A shown in FIG. 15). The NE3
sets .lambda.a, .lambda.b, and .lambda.c to Through according to a
time table (B shown in FIG. 15). In this way, the settings of the
time period T1 are completed. When the time period T2 is reached,
the NE1 set as the management NE transmits a switching trigger TRG2
(D shown in FIG. 15) to the respective NEs by using an OSC optical
signal, and the respective NEs make wavelength settings by using
the trigger as a cue according to a set time table. The NE2
wavelength-converts .lambda.a into .lambda.b, transmits .lambda.b
to the NE3, drops .lambda.b, and adds .lambda.a according to a time
table (A shown in FIG. 15). The NE3 sets .lambda.b to Add/Drop, and
also sets .lambda.b and .lambda.c to Through according to a time
table (B shown in FIG. 15). Also the settings from the NE4 to the
NE1 are similar to the above described ones. The settings of a time
table in each of the NEs can be changed from all of the NEs by
using an OSC optical signal.
[0073] FIG. 16 is a flowchart explaining the process executed by
each NE according to the fourth preferred embodiment of the present
invention.
[0074] Step S45 is waiting for an event to occur. If the trigger
TRG T1 is received as in step S46, the line setting T1 is made in
step S47. Then, in step S48 a completion notification of the line
setting T1 is transmitted. In step S49, it is determined whether or
not the completion notification of the line setting T1 is received.
If the completion notification is determined not to be received, an
alarm is given. If the completion notification is determined to be
received, the process is terminated.
[0075] If the trigger TRG T2 is determined to be received as in
step S50, the line setting T2 is made in step S51. Then, in step
S52, a completion notification of the line setting T2 is
transmitted. In step S53, it is determined whether or not the
completion notification of the line setting T2 is received. If the
completion notification is determined to be received, the process
is terminated. If the completion notification is determined not to
be received, an alarm is given. If a time table rewrite instruction
is received as in step S54, the time table is rewritten in step
S55, and the process goes back to step S45.
[0076] FIG. 17 is a flowchart showing the details of a process
executed by the SW unit.
[0077] When the setting of the wavelength .lambda.x is started, it
is determined in step S60 whether or not a Through instruction of
.lambda.x is received. If the Through instruction is determined to
be received, .lambda.x on the DMUX side is branched to the coupling
unit in step S63, and .lambda.x from the branch unit is coupled to
the MUX side in step S64. Here, the process is terminated.
[0078] If the Through instruction is determined not to be received
in step S60, it is further determined in step S61 whether or not a
Drop instruction of .lambda.x on the DMUX side is received. If a
result of the determination made in step S61 is "Yes", .lambda.x on
the DMUX side is branched to the Drop side in step S65. Then, in
step S66, it is determined whether or not an Add instruction of
.lambda.x on the MUX side is received. If a result of the
determination made in step S66 is "Yes", .lambda.x from the Add
side is coupled to the MUX side in step S69, and the process is
terminated. If the result of the determination made in step S66 is
"No", it is determined in step S67 whether or not a wavelength
conversion instruction for .lambda.x on the MUX side is received.
If the instruction is determined to be received, .lambda.x from the
wavelength converting unit is coupled to the MUX side in step S70.
If the instruction is determined not to be received, the process is
terminated.
[0079] If the Drop instruction is determined not to be received in
step S61, it is determined in step S62 whether or not a wavelength
conversion instruction for .lambda.x on the DMUX side is received.
If a result of the determination made in step S62 is "Yes",
.lambda.x on the DMUX side is branched to the wavelength converting
unit. If the result of the determination made in step S62 is "No",
the process goes to step S66.
[0080] FIG. 18 is a flowchart explaining the operations of the
wavelength converting unit.
[0081] In step S75, it is determined whether or not an instruction
to convert the wavelength .lambda.x into .lambda.y is received. In
step S76, .lambda.x from the branch unit is converted into an
electric signal Ex by the O/E Mod. In step S77, an electric path is
switched to the E/O Mod converting the electric signal Ex into
.lambda.y. In step S78, the electric signal Ex is converted into
.lambda.y by the E/O Mod, and the process is terminated.
* * * * *